Heavy current bushing



Sept. 13, 193:2.

A. O. AUSTIN HEAVY CURRENT BUSHING Filed Sep. 8, 1928 5 Sheets-Sheet 1 INVENTOR &a 1/ I (4 24/41 Q ATTORNEY Sept. 13, 1932. A, U5 1,876,581

HEAVY CURRENT BUSHING Filed Sept. 8, 1928 5 Sheets-Sheet 2 INVENTOR Arf/wr 0. flusf/h I A TT ORNE Y Sept. 13, 1932. A. o. AUS I N 1,876,581

HEAVY CURRENT BUSHING Filed Sept. 8, 1928 5 Sheets-Sheet 5 my 7 Fly. 6

H ENTOR flrf/wr 0. Aw/m BY @ZKULL QTTORNEY Patented Sept. 13, 1932 UNITED STATES PATENT OFFICE ARTHUR 0. AUSTIN, F NEAR BARBERTON, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE OHIO BRASS COMPANY, OF MANSFIELD, OHIO, A CORPORATION OF NEW JERSEY HEAVY CURRENT BUSHING Application filed September 8, 1928. Serial No. 304,763.

This invention relates to insulator bushings for electrical conductors and has for one of its objects the provision of bushings especially adapted for use with heavy current conductors.

Another object is to provide threaded means for tightening the joint between the bushing and a non-circular conductor. A further object is to provide a bushing which lends itself to installation in a manner tominimize eddy current losses in the wall through which the bushing extends. A further object' is to provide a bushing which may be economically installed and which will insure a tight joint between the conductor and housing member. Other objects and advantages will appear from the following description.

The invention is exemplified in the combination and arrangement of parts shown in the accompanying drawings and described in the following specification, and it is more particularly pointed out in the appended claims.

several leads.

In the drawings:

Fig. 1 is an elevation with parts in section illustrating one embodiment of the present invention.

Fig. 2 is an elevation partly in section at right angles to the plane of Fig. 1.

Fig. 3 is a bottom plan of the device shown in Figs. 1 and 2.

Fig. 4 is a section on line 4-4 of Fig. 1.

Figs. 5 and 6 are views similar to Figs. 1 and 2 respectively, showing a different form of the invention.

Figs. 7 and 8 are views similar to Figs. 1 and 2 respectively, showing still another form of the invention.

Fig. 9 is a fragmentary plan of a portion of a transformer housing with a plurality of bushing insulators in place.

Where the currents are high in transformer leads, it is necessary to bring the leads out of the transformer case in such a way that eddy currents will not be set up in the case, especiallywhere the case is of a magnetic material. In order to do this, it is usually necessary that the leads come out through bushings placed in a non-magnetic cover, which encloses the Where all the leads pass through an opening in the cover plate, which entirely surrounds the leads, the total resulting effect of the current tending to set up a flux in the plate is practically zero, owing to the fact that the incoming current oifsets the outgoing current. Where the currents are high, and the incoming and the outgoing currents enclose a portion of the case so as to set up a magnetic field, the energy loss may be appreciable, especially where this current is set up in a magnetic material.

The loss may cause damage owing to excessive temperature and, in addition, is a waste of energy. In transformers which have a great many leads or where the current is such as to require leads of very large section, there is frequently considerable difliculty in reducing the eddy currents sufliciently without incurring a considerable cost for bushings and cover. The present inven tion makes it possible not only to provide heavy current outlets at lower cost, but the cost of the case or outlet plate is greatly reduced. It, of course, is evident that the construction is not necessarily confined to transformers, but may be used for wall bushings, disconnecting switches, or in any place where it is desired to handle heavy currents with out causing excessive losses.

In the form of the invention shown in Fig. 1, a bushing having an insulating member 10 is provided with a flange 11 for bolting onto the case and a rectangular lead 12 for carrying the current. The rectangular lead has a flange 13 which may be brazed or formed on the rectangular member. This flange is made of a non-magnetic material such as copper or bronze. A gasket 14; is placed between the cap and the dielectric member 10, although in some cases, it may be advisable to cement the cap portion to the dielectric member as is general practice at the present time. The conducting member 12 is provided with a collar or flange 15 which has an opening so that it will slide over the member 12.. The member 12 has holes 16 tapped in at an angle which will accommodate the cap screws 17. The cap screws pass through slotted holes in the flange 15 so that when the cap screws 17 are tightened up,

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the flange or collar 15 will be free to move against the end of the dielectric member 10. A gasket 18 is usually provided between the flange or collar 15 and the dielectric member 10. By tightening up the cap screws 17, the conducting member 12 is placed in tension. This draws the flange 13 against the gasket 14 and insures a tight fit for the bushing. The pressure exerted by the cap screws causes the flange 15 to bear against the conducting member 12 and against the gasket 18. This holds the lower end of the conducting member 12 firmly in place so that it will not be free to vibrate under the magnetic forces. The arrangement makes it possible to use the rectangular conducting members as well as flat members in the bushing without providing a threaded collar for tightening up.

in general, where a rectangular bar is used, it will be placed in a bushing having an elliptical or rectangular opening, although it is evident that the scheme will work equally well with a bushing with a circular opening where the hole in the bushin is large enough to allow the conducting member to pass. The conducting member is frequently made in one piece having a slot 19. This arrangement makes it possible to insure an absolutely tight bushing so that moisture cannot enter between the parts. Where large currents are involved, the bushings maybe provided with several slots at each end. The flange 11 is usually cemented to the bushing and forms a means of attaching the bushing to the transformer cover.

Figs. 5 and 6 show a somewhat different form of the invention which is generally used where the voltage is less than 4000 volts, although the type may be made for much higher voltages. The conducting bar 12 is provided with a flange 13 brazed or welded to the conducting member 12. The tightening cap screws 17 are similar to those shown in Fig. 1. This type of bushing is particularly applicable where a large number of outlets are desired, as in furnace transformers where the currents are high and the voltage usually comparatively low. In transformers of this type, the cost ofthe cover to which the bushings are attached is a very-appreciable item. The improved type of bushing shown in Figs. 5 and 6 makes it possible to provide a cover or outlet at much lower cost than is otherwise possible, as the cover may be made from a piece of sheet metal such as sheet copper or aluminum.

Fig. 9 shows a cover plate 22 applied to a housing 22 and supporting a number of outlets comprising conductors 12 having flanges l3 bearing on insulators 20.

The dielectric member is made up in three parts, 20, 21 and 26. The dielectric member 20 and the dielectric member 21 are placed on either side of the cover plate 22. Gaskets are provided at 23 and 24 so that when' the cap screws 17 are tightened up, a tight joint is provided at the gasket 14 and between the dielectric members 20 and 21 and the cover plate 22. I

The cover plate 22 may be readily made from sheet material by providing a hole of the proper size or by turning up a lip or flange 25 in addition to providing the hole of proper size. This flange tends to center the bushing properly in the opening, stiffens the plate and prevents water running into the transformer case, should the gasket for any reason not provide a tight joint. In order to provide additional insulation between the cover plate 22 and the conducting member 12, an insulating sleeve 26 is provided or is slipped over the conducting member 12. This sleeve may be fibre, paper, or any suitable insulating material. Any number of cap screws 17 may be provided depending upon the size of the bar and the pressure required to maintain a tight joint.

In the modification shown in Figs. 7 and 8, the dielectric member 30 is provided with a bearing surface 31 and a groove 32 for accommodating the upturned lip 25 of the cover. The dielectric member 30 has a projecting end 33 which runs through the hole in the cover 22 so as to interpose insulation in the path between the cover plate 22 and conducting member 12. A suitable dielectric member 34 is placed below the cover plate 22 and the flange 18 bears upon this member. WVhen the cap screws 17 are tightened up, the joints between the flange 18 and the dielectric member 34 and between the dielectric members 34 and 30 and the case, as well as between the cap 13 and the dielectric member 30 are all tightened up. This insures a tight joint and eliminates an cementing. This is desirable, particularly where the conductin members are large, as it is exceedingly di cult under these conditions, to provide a tight joint since the difference in expansion and contraction between the conducting member and the dielectric members will cause the joint to leak or will burst the dielectric member.

In Figs. 7 and 8 the cap screws, instead of threading directly into the conducting member 12, are threaded into a member 35 which passes through an opening in the conducting member. This arrangement permits the conducting member to be slipped through a hole in the member 30 but little larger than the conductor after which the bar 35 may be passed through a transverse opening and the tightening cap screws 17 screwe into place. Where it is desired to eliminate air spaces in the bushing at the lower end, a hole 36 may be placed in the flange and a hole 37 in the dielectric compression sleeve. This will permit-the air to escape from the space tobe filled with oil.

I claim: s

1. In combination, a metallic plate having an opening therethrough, the edge of said plate surrounding said opening being transversely bent forming a flange at one side only of said plate, a conductor extending through said opening, a tubular insulator surrounding said conductor and having one end thereof arranged to bear upon the face of said plate outside of said flange, a flange secured to said conductor and arranged to bear on the end of said tubular insulator opposite said plate, and means including a threaded member for exerting tension on said conductor to draw the flange of said conductor against the end of said tubular insulator and to press said insulator against said plate.

2. In combination, a tubular insulator, a conductor extending through said insulator and having a flange thereon arranged to engage one end of said insulator, a bearing member having bearing connection with said insulator in spaced relation to said flange, and a threaded member extending at an oblique angle to the axis of said insulator and engaging said conductor and bearing member for exerting tension on said conductor to draw said flange against the end of said insulator.

3. In combination, a tubular insulator, a conductor extending through said insulator and having a flange thereon for engaging one end of said insulator to close said end, a flange having bearing connection with the opposite end of said insulator, and a threaded member extending obliquely to the axis of said conductor through said second flange and engaging said conductor to draw said conductor through said insulator and hold said first flange against the end of said insulator.

4. In combination, a tubular insulator, a

conductor of non-circular cross section we tending through said insulator and having a flange thereon engaging one end of said insulator to close said end, a bearing memher having bearing connection with said insulator, and threaded members extending obliquely to the axis of said conductor through said bearing member into said conductor from opposite sides of said conductor for exerting tension on said conductor to hold said flange against the end of said insulator.

5. In combination, a tubular insulator, a conductor of non-circular cross section extending through said insulator and having a flange thereon engaging one end of said insulator to close said end, a bearing member having bearing connection with said insulator, and a threaded member connecting said bearing member and the non-circular portion of said conductor and of such form and'so positioned that it exerts tension on said conductor to hold said flange in contact with the end of said insulator.

6. In combination, a tubular insulator, a conductor of non-circular cross section extending through said insulator and having a flange thereon engaging one end of said insulator to close said end, a threaded memberhaving bearin connections with said insulator and conc uctor and rotatable upon an axis other than the axis of said conductor and of such form and so positioned that it exerts tension on said conductor to hold said flange against the end of said insulator and an abutment for said threaded member bearing on said insulator.

7. In combination, a bushing insulator, a conductor extending through said insulator and having a flange for engaging one end of said insulator, a flange having an opening therethrough for receiving the opposite end of said conductor and engaging the end of said insulator opposite said first named flange, and bolts extending through said last named flange and having threaded connection with said conductor and of such form and so positioned that they exert tension on said conductor to clamp said insulator be tween said flanges.

8. The combination with a plate having an opening therethrough, of a conductor extending through said plate, a pair of tubular insulators surrounding said conductor at opposite sides of said plate and having their ends arranged tobear upon opposite, faces of said plate, a flange on said conductor arranged to engage the end of one of said tubular insulators, a bearing member arranged to engage the opposite end of the other of said tubular insulators, and bolts engaging said bearing member and having threaded connection with said conductor and of such form and so positioned that they press said tubular insulators against said plate and hold said flange against the end of said first named insulator.

9. The combination with a plate having an opening therethrough, a conductor hav ing oppositely disposed flat faces extending through said opening, tubular insulators surrounding said conductor at opposite sides of said plate and having their adjacent ends arranged to bear against opposite faces of said plate, a flange secured to said conductor for engaging the outer end of one of said insu-' lators, a bearing member movable relative to said conductor for engaging the opposite end of the other of said insulators, and bolts extending through said bearing member and obliquely threaded into said conductor from opposite flat faces thereof for holding said tubular insulators against said plate and for holding said flange against the end of one of said insulators.

10. In combination, a platehaving an opening therethrough and a laterally bent flange surrounding said opening, a conductor extending through said opening, tubular insulators surrounding said conductor at opposite sides of said plate and having their adjacent ends arranged to bear on Opposite faces of sai d pl ate, a dielectricsleeve extending through the opening of said plate between said conductor and the inner edge of said plate and overlapping the joint between said tubular insulators, a flange secured to said conductor and bearing against the outer end of one of said tubular insulators to close said end, a flange having an opening therethrough for receiving said conductor adjacent the opposite end of the other of said insulators, and screws extending through said flange and having their axes disposed at an angle to the axis of said eonductor, said screws being threaded intosaid conductor from opposite sides thereof.

ll. Entrance means for aplurality of circuits entering a housing comprising a nonmagnetic cover plate having a plurality of oblong openings therethrough, a reinforcement flange suirouiuling each of said openings and each consisting of a bent-up margin of the plate surrounding the opening, a conductor lead extending through each of said openings and having an oblong cross-section,

a bushing insulator comprising a pair of dielectric sleeves for each of said conductor leads. said sleeves bearing on opposite sides of said plate and having an'oblong shape in cross-section to conform to the shape of the opening through said plate. a flange attached to each of said conductor'leads and bearing against one of said dielectric sleeves, a second flange bearing against the other dielectric sleeve, and screws engaging said second flange and threaded into said conductor lead and of such form and so positioned that they exert tension on said conductor lead to press sai'd insulator sleeves against opposite faces of said plate.

12. Entrance means for an electric circuit comprising a cover plate having an opening therethrough, the margin of said plate being bent upwardly about said opening to form a reinforcing flange, dielectric sleeves at opposite sides of said plate surrounding said opening and bearing against opposite faces of said plate, a conductor lead extending through said opening and through said sleeves, means connected to said lead and bearing on said sleeves to press said sleeves against opposite faces of said plate, and a supplemental insulating sleeve surrounding said conductor and extending through said opening between said conductor and said reinforcing flange and overlapping the joint between said cover plate and said first-named sleeves.

13. In combination a tubular insulator, a conductor of non-circular cross section extending through said insulator, a stop secured to said conductor and bearing against said insulator, a threaded member engaging the non-circular portion of said conductor, and means engaging said threaded member and said insulator and forming an abutment for said threaded member, said threaded member being of such form and so positioned that it will exert tension on said conductor for pressing said stop toward said insulator.

14. The combination with a tubular insulater, of a conductor extending througlrsaid insulator and having a stop thereon for engaging one end of said insulator, said conductor having a transverse opening therethrough, a key disposed in said opening, an abutment member engaging the other end of said insulator, and threaded members engaging said key and said abutment and being formed and positioned for exerting tension on said conductor and for holding said conductor in place in said tubular insulator.

15. The combination with a tubular insulator, of a conductor extending tl1erethrough and having a stop for engaging one end of said insulator, said conductor having a transverse opening therethrough, a key extending through said opening, a bearing member engaging said insulator, and threaded means connecting said key and bearing member for holding said conductor in place in said tubular insulator.

16. The combination with a plate having an opening therethrough and a flange surrounding said opening, of a tubular insulator extending through said opening and having a shoulder thereon arranged to bear upon said plate outside of said flange, a conductor extending through said insulator, means secured to said conductor for engaging said insulator, said conductor having a transverse opening therethrough, a key extending through said opening, a second tubular insulator arranged to engage the face of said plate opposite said shoulder, a bearing member engaging said second named tubular insulator and having an opening through which said conductor extends, and threaded means engaging said bearing member and key for holding said tubular insulators in place against said plateand for holding said conluctor in place in said tubular insulators.

Intestimony whereof I have signed my name to this specification this 6th day of September, A. D. 1928.

' AUTHUR O. AUSTIN. 

